v6ops Working Group N. Hilliard
Internet-Draft INEX
Intended status: Informational D. Freedman
Expires: December 11, 2012 Claranet
June 9, 2012
A Discard Prefix for IPv6draft-ietf-v6ops-ipv6-discard-prefix-05
Abstract
Remote triggered black hole filtering describes a method of
mitigating the effects of denial-of-service attacks by selectively
discarding traffic based on source or destination address. Remote
triggered black hole routing describes a method of selectively re-
routing traffic into a sinkhole router (for further analysis) based
on destination address. This document updates the IPv6 Special
Purpose Address Registry by explaining why a unique IPv6 prefix
should be formally assigned by IANA for the purpose of facilitating
IPv6 remote triggered black hole filtering and routing.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 11, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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Internet-Draft IPv6 Discard Prefix June 20121. Introduction
Remote triggered black hole (RTBH) filtering describes a class of
methods of blocking IP traffic either from a specific source
([RFC5635]) or to a specific destination ([RFC3882]) on a network.
RTBH routing describes a class of methods of re-routing IP traffic
destined to the attacked/targeted host to a special path (tunnel)
where a sniffer could capture the traffic for analysis. Both these
methods operate by setting the next-hop address of an IP packet with
a specified source or destination address to be a unicast prefix
which is connected locally or remotely to a router's discard, null or
tunnel interface. Typically, reachability information for this
prefix is propagated throughout an autonomous system using a dynamic
routing protocol such as BGP ([RFC3882]). By deploying RTBH systems
across a network, traffic to or from specific destinations may be
selectively black-holed or re-routed to a sinkhole device in a manner
which is efficient, scalable and straightforward to implement.
On some networks, operators configure RTBH installations using
[RFC1918] address space or the address blocks reserved for
documentation in [RFC5737]. This approach is inadequate because RTBH
configurations are not documentation, but rather operationally
important features of many public-facing production networks.
Furthermore, [RFC3849] specifies that the IPv6 documentation prefix
should be filtered in both local and public contexts. On this basis,
it is suggested that both private network address blocks and the
documentation prefixes described in [RFC5737] are inappropriate for
RTBH configurations, and that a dedicated IPv6 prefix should be
assigned instead.
This document updates the IPv6 Special Purpose Address Registry
[IANA-IPV6REG].
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. A Discard Prefix for IPv6
For the purposes of implementing an IPv6 remote triggered black hole
configuration, a unicast address block is required. There are
currently no IPv6 unicast address blocks which are specifically
nominated for the purposes of implementing such RTBH systems.
While it could be argued that there are other addresses and address
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Internet-Draft IPv6 Discard Prefix June 2012
prefixes which could be used for this purpose (e.g. documentation
prefixes, private address space), or that an operator could assign an
address block from their own address space for this purposes, there
is currently no operational clarity on what address block would be
appropriate or inappropriate to use for this purpose. By assigning a
globally unique discard prefix for IPv6, the IETF will introduce good
practice for the implementation of IPv6 RTBH configurations and will
facilitate operational clarity by allowing operators to implement
consistent and deterministic inter-domain prefix and traffic
filtering policies for black-holed traffic.
As [RFC3882] and [RFC5635] describe situations where more than one
discard address may be used for implementing multiple remote
triggered black hole scenarios, a single address is not sufficient to
cover all likely RTBH situations. Consequently, an address block is
required.
3. Operational Implications
This assignment MAY be carried in a dynamic routing protocol within
an autonomous system. The assignment SHOULD NOT be announced to or
accepted from third party autonomous systems and IPv6 traffic with a
destination address within this prefix SHOULD NOT be forwarded to or
accepted from third party autonomous systems. If the prefix or a
subnet of the prefix is inadvertently announced to or accepted from a
third party autonomous system, this may cause excessive volumes of
traffic to pass unintentionally between the the two networks, which
would aggravate the effect of a denial-of-service attack.
On networks which implement IPv6 remote triggered black holes, some
or all of this network block MAY be configured with a next-hop
destination of a discard or null interface on any or all IPv6 routers
within the autonomous system.
4. IANA Considerations
This document directs IANA to record the allocation of the IPv6
address prefix xxxx/64 as a discard-only prefix in the IPv6 Address
Space registry and to add the prefix to the IPv6 Special Purpose
Address Registry [IANA-IPV6REG]. No end party is to be assigned this
prefix. The prefix should be allocated from ::/3.
5. Security Considerations
As the prefix specified in this document ought not normally be
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